Rapid and Direct Preparation of Lignin Nanoparticles from Alkaline Pulping Liquor by Mild Ultrasonication

<div> <div> <div> <p>Existing methods for making MIDA boronates require harsh conditions and complex procedures to achieve dehydration. Here we disclose that a pre-dried form of MIDA, MIDA anhydride, acts as both a source of the MIDA ligand and an in situ desiccant to enable a mild and simple MIDA boronate synthesis procedure. This method expands the range of sensitive boronic acids that can be converted into their MIDA boronate counterparts. Further utilizing unique properties of MIDA boronates, we have developed a MIDA Boronate Maker Kit which enables the direct preparation and purification of MIDA boronates from boronic acids using only heating and centrifuge equipment that is widely available in labs that do not specialize in organic synthesis. </p> </div> </div> </div>

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α-Ketophosphonates in the Synthesis of α-iminophosphonates

Current Green Chemistry ◽

10.2174/2213346107666200226095806 ◽

2020 ◽

Vol 7 (2) ◽

pp. 226-238

Author(s):

Petro P. Ony`sko ◽

Tetyana I. Chudakova ◽

Vladimir V. Pirozhenko ◽

Alexandr B. Rozhenko

Keyword(s):

Bond Cleavage ◽

Direct Synthesis ◽

Equilibrium Mixture ◽

Primary Amines ◽

Alkyl Amines ◽

Protic Solvents ◽

Metallic Salts ◽

Direct Preparation ◽

Stage Synthesis ◽

Aprotic Dipolar Solvent

The potentialities of condensation of α-ketophosphonates with primary amines for direct synthesis of α-iminophosphonates have been revealed. Diesters of α-ketophosphonic acids react with the primary amines by two competitive pathways: with a formation of α-iminophosphonates or a C-P bond cleavage resulting in a hydrogen phosphonate and an acylated amine. In many cases, the latter undesirable pathway is dominant, especially for more nucleophilic alkyl amines. Using metallic salts of α-ketophosphonates avoids the C-P bond cleavage, allowing direct preparation of α-phosphorylated imines by the reaction with primary amines. This strategy provides an atom economy single-stage synthesis of iminophosphonates – precursors of bio relevant phosphorus analogs of α-amino acids. Methyl sodium iminophosphonates, bearing aryl or heteryl substituents at the imino carbon atom exist in solutions at room temperature as an equilibrium mixture of Z- and E-isomers. A configuration of the C=N bond can be controlled by the solvent: changing the aprotic dipolar solvent DMSO-d6 by water or alcohols leads to the change from a predominant Z-isomer to almost an exclusive E-form. In contrast, diesters of the respective iminophosphonates exist in non-protic solvents predominantly in Econfiguration. The solvent effect on E-Z stereochemistry is demonstrated by DFT calculations.

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THE DIRECT PREPARATION OF CRYSTALLINE UROBILIN FROM BILIRUBIN

Journal of Biological Chemistry ◽

10.1016/s0021-9258(18)71415-4 ◽

1953 ◽

Vol 200 (2) ◽

pp. 691-696 ◽

Cited By ~ 1

Author(s):

C.J. Watson

Keyword(s):

Direct Preparation

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Recycling Waste Cotton Cloths for the Isolation of Cellulose Nanocrystals: A Sustainable Approach

Polymers ◽

10.3390/polym13040626 ◽

2021 ◽

Vol 13 (4) ◽

pp. 626

Author(s):

Siti Hajar Mohamed ◽

Md. Sohrab Hossain ◽

Mohamad Haafiz Mohamad Kassim ◽

Mardiana Idayu Ahmad ◽

Fatehah Mohd Omar ◽

...

Keyword(s):

Electron Microscopy ◽

Cellulose Nanocrystals ◽

Value Added ◽

Crystallinity Index ◽

Attenuated Total Reflection ◽

Cellulose Content ◽

Scanning Calorimetry ◽

Good Thermal Stability ◽

Alkaline Pulping ◽

Hydrolysis Of Cellulose

There is an interest in the sustainable utilization of waste cotton cloths because of their enormous volume of generation and high cellulose content. Waste cotton cloths generated are disposed of in a landfill, which causes environmental pollution and leads to the waste of useful resources. In the present study, cellulose nanocrystals (CNCs) were isolated from waste cotton cloths collected from a landfill. The waste cotton cloths collected from the landfill were sterilized and cleaned using supercritical CO2 (scCO2) technology. The cellulose was extracted from scCO2-treated waste cotton cloths using alkaline pulping and bleaching processes. Subsequently, the CNCs were isolated using the H2SO4 hydrolysis of cellulose. The isolated CNCs were analyzed to determine the morphological, chemical, thermal, and physical properties with various analytical methods, including attenuated total reflection-Fourier transform-infrared spectroscopy (ATR-FTIR), field-emission scanning electron microscopy (FE-SEM), energy-filtered transmission electron microscopy (EF-TEM), X-ray diffraction (XRD), thermogravimetric analysis (TGA), and differential scanning calorimetry (DSC). The results showed that the isolated CNCs had a needle-like structure with a length and diameter of 10–30 and 2–6 nm, respectively, and an aspect ratio of 5–15, respectively. Additionally, the isolated CNCs had a high crystallinity index with a good thermal stability. The findings of the present study revealed the potential of recycling waste cotton cloths to produce a value-added product.

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